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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201204012448.26546-2-wqu@suse.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 4.12.20 г. 3:24 ч., Qu Wenruo wrote: > [BUG] > When running the following script, btrfs will trigger an ASSERT(): > > #/bin/bash > mkfs.btrfs -f $dev > mount $dev $mnt > xfs_io -f -c "pwrite 0 1G" $mnt/file > sync > btrfs quota enable $mnt > btrfs quota rescan -w $mnt > > # Manually set the limit below current usage > btrfs qgroup limit 512M $mnt $mnt > > # Crash happens > touch $mnt/file > > The dmesg looks like this: > > assertion failed: refcount_read(&trans->use_count) == 1, in fs/btrfs/transaction.c:2022 > ------------[ cut here ]------------ > kernel BUG at fs/btrfs/ctree.h:3230! > invalid opcode: 0000 [#1] SMP PTI > RIP: 0010:assertfail.constprop.0+0x18/0x1a [btrfs] > btrfs_commit_transaction.cold+0x11/0x5d [btrfs] > try_flush_qgroup+0x67/0x100 [btrfs] > __btrfs_qgroup_reserve_meta+0x3a/0x60 [btrfs] > btrfs_delayed_update_inode+0xaa/0x350 [btrfs] > btrfs_update_inode+0x9d/0x110 [btrfs] > btrfs_dirty_inode+0x5d/0xd0 [btrfs] > touch_atime+0xb5/0x100 > iterate_dir+0xf1/0x1b0 > __x64_sys_getdents64+0x78/0x110 > do_syscall_64+0x33/0x80 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > RIP: 0033:0x7fb5afe588db > > [CAUSE] > In try_flush_qgroup(), we assume we don't hold a transaction handle at > all. This is true for data reservation and mostly true for metadata. > Since data space reservation always happens before we start a > transaction, and for most metadata operation we reserve space in > start_transaction(). > > But there is an exception, btrfs_delayed_inode_reserve_metadata(). > It holds a transaction handle, while still trying to reserve extra > metadata space. > > When we hit EDQUOT inside btrfs_delayed_inode_reserve_metadata(), we > will join current transaction and commit, while we still have > transaction handle from qgroup code. > > [FIX] > Let's check current->journal before we join the transaction. > > If current->journal is unset or BTRFS_SEND_TRANS_STUB, it means > we are not holding a transaction, thus are able to join and then commit > transaction. > > If current->journal is a valid transaction handle, we avoid committing > transaction and just end it > > This is less effective than committing current transaction, as it won't > free metadata reserved space, but we may still free some data space > before new data writes. > > Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=1178634 > Fixes: c53e9653605d ("btrfs: qgroup: try to flush qgroup space when we get -EDQUOT") > Reviewed-by: Filipe Manana > Signed-off-by: Qu Wenruo > Signed-off-by: David Sterba Wasn't this submitted already? Also are you going to turn the example script into a fstest?